Applicants claim, under 35 U.S.C.xc2xa7119, the benefit of priority of the filing date of Mar. 28, 2001 of a German patent application, copy attached, Serial Number 101 15 549.2, filed on the aforementioned date, the entire contents of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to an angle measuring instrument with two components, which can be rotated in relation to each other. The present invention also relates to the use of this instrument in connection with machine tools, or processing centers, or printing presses.
2. Discussion of Related Art
Angle measuring instruments of this type are used for measuring the rotations of a shaft over one or several revolutions. In this case, the rotation is detected either incrementally or absolutely, as a function thereof the issued measured value is a sequence of counting pulses, a count value or a code word. In connection with toothed racks or threaded spindles it is also possible to measure linear movements with such angle measuring instruments. Angle measuring instruments are employed in connection with machine tools in particular, or in processing centers, both for the measurement of linear and rotary movements. The determination of the angles of rotation to an exactness of a few seconds of angle is of critical importance, for example for turntables or swing heads of machine tools, the C axes of lathes, but also in print units of printing presses. Such angle measuring instruments are often employed at locations where comparably rough conditions of the surroundings prevail. For example, the penetration of lubricants or cooling fluids is a frequent cause of the failure of angle measuring instruments in the operation of machine tools, or processing centers.
An angle measuring instrument is disclosed in Laid Open Document JP 9-178523A, which has a flange on the rotor, so that a gap is created between the flange and the stator element. By the provision of grooves in the flange it is intended during the operation to convey solid particles out of the gap as a result of centrifugal force.
This known angle measuring instrument has the disadvantage that the front face of the stator is not suited to keep standing fluids away from the seal, on the one hand, and on the other to simultaneously serve as an installation surface. Added to this is that the structural space available for the stator housing is not optimally utilized.
An object of the present invention is therefore based on providing an angle measuring instrument into which fluids from the surroundings cannot enter.
This object is attained by an angle measuring instrument that includes an outer component having a front face and an inner component, wherein the outer component is rotated relative to the inner component about an axis of rotation and the outer component lies further from the axis of rotation than the inner component along a radial direction with respect to the axis of rotation. A seal formed between the outer component and the inner component and wherein the front face includes a conduit which leads radially outward and is located lower with respect to the front face.
It is intended to employ the angle measuring instrument in accordance with the present invention in rotatable elements of machine tools, or processing centers, or printing presses, in particular with turntables of machine tools.
Accordingly, the angle measuring instrument includes a component located on the inside and a component located on the outside which advantageously completely encloses the one located on the inside over the circumference. The component located on the inside is often designed as a rotor, in particularly a rotatable hollow shaft. In that case, the component located on the outside is designed as a stator, whose flange-like designed housing element is simultaneously used in a preferred embodiment as an installation face, for example on a turntable of a machine tool.
Because of this structural shape, the angle measuring instrument can be mounted simply and precisely on a provided installation surface. Further than that, by the device in accordance with the present invention it is possible to assure a satisfactory utilization of the volume of the housing. Added to this is that, by the construction in accordance with the present invention, the seal and possibly the shaft end are set back in relation to the front face of the stator housing, and therefore are protected to a large extent against exterior mechanical effects.
Further advantages, as well as details of the method in accordance with the present invention ensue from the following description of a possible exemplary embodiment by the attached drawings. In the exemplary embodiment described below, the housing of the angle measuring instrument is made of a steel part and an aluminum part. It is apparent that the present invention is not limited to this selection of materials, it should be stressed that the present invention relates to a structural shape of an angle measuring instrument, or of its use, and not to the selection of the material of one of its components. The use of other materials, for example from the group of plastic materials, is quite customary, in particular for the housing.